Sound translating apparatus



Nov. 9, 1937. H. F. HOPKINS SOUND TRANSLATING APPARATUS Filed Jan. 30, 1937 HHWHIHIMMHH INVENTOR H. F. HOP/(INS mm a 7M A T TOR/V5 V Patented Nov. 9, 1937 UNITED STATES PATENT OFFICE! Telephone Laboratories,

Incorporated, New

York, N. Y., a corporation of New York Application January 30, 1937, Serial No. 123,219

13 Claims.

This invention relates to sound translating apparatus and more particularly to loud-speakers suitable for outdoor announcing systems.

In outdoor announcing systems, the diaphragms of the sound translating devices, such as direct acting or horn type loud-speakers, may be sub- Jected to subnormal or abnormal atmospheric conditions which may impair the operation of the devices or cause deformation or even destruction 10 of the diaphragms. This is particularly true in announcing systems on warships wherein of necessity certain of the loud-speakers are mounted in the vicinity of the guns. Firing of the guns produces intense pressure waves or sub-atmos- 15 pheric pressures adjacent the diaphragms of the loud-speakers as a result of which the diaphragms may buckle or rupture so that the devices of which they form a part are rendered wholly or partly inoperative.

20 One object of this invention is to prevent impairment of sound translating devices by subnormal or abnormal atmospheric conditions to which the devices may be subjected. More speciflcally, one object of this invention is to prevent 25 rupture or deleterious deformation of diaphragm in loud-speakers suitable for use in outdoor announcing systems.

In accordance with one feature of this invention means are provided for automatically sealing 30 the exposed surface of the diaphragm from the atmosphere when the atmospheric pressures in the vicinity of the loud-speaker are other than normal.

In accordance with another feature of this in- 35 vention means are provided for rendering the sealing means inoperative when normal atmospheric conditions again obtain after a period of other than normal conditions.

The invention and the foregoing and other 40 features thereof will be understood clearly and fully from the following detailed description with reference to the illustrative embodiments shown in the accompanying drawing in which:

Fig. 1 is a schematic and diagrammatic view of 5 a loud-speaker and a protective system therefor illustrative of one embodiment of this invention;

Fig. 2 is-a view in cross-section of a portion of a loud-speaker constructed in accordance with this in Fig. 1 comprises a sound translating device, such as a loud-speaker, including a diaphragm l one surface of which is acoustically coupled to the atmosphere through an acoustic transducer, such as a horn ll. Disposed between the diaphragm I0 and the inlet or throat of the horn I l is a movable plug member l2 adapted to close the throat of the horn and thereby to seal the diaphragm from the atmosphere. A magnetic member or armature l'3 is coupled to the plug l2 and is associated with a solenoid or actuating coil H, the armature and plug member being so disposed that when the solenoid or coil is deenergized the diaphragm III is in communication with the atmosphere through the horn ll.

The solenoid or coil I4 may be energized through a. series circuit including a source [5, such as a battery, the winding I6 of a relay, and two micro-switches I1 and I8 connected in parallel. The switches i1 and 18 may be mounted in 20 a water-tight casing l8 and are adapted to be actuated by vibratile members, such as auxiliary diaphragms 20 and 2|, respectively, sensitively responsive to pressure waves, the diaphragms being associated with the movable contact of the switches as by links or push rods 22. The diaphragms may be supported by the housing and a suitable frame 50. As shown in Fig. 1, the switches l1 and I8 preferably are so arranged that the former will close when its associated diaphragm 20 moves inwardly with respect to the housing and the latter will close when its associated diaphragm 21 moves outwardly.

The relay is provided with a contact 23, com

nected to one end of the winding l6, and an armature 24 in series with a switch 25, one terminal of which is connected to one end of the solenoid II as shown.

The system above described may be installed in the vicinity of a source 26 of intense pressure 4 waves, such as a gun aboard a warship. Preferably the auxiliary diaphragms 20 and 2| are positioned materially nearer the source 26 than the loud-speaker so that when the source operates the switch II or i8 or both, will be actuated before abnormal or subnormal atmospheric pressures are produced in the vicinity of the diaphragm Hi.

When the source 26 operates, as when the gun is fired, intense pressure waves are created so that either abnormal or subnormal pressures are produced adjacent the loud-speaker and the diaphragms l1 and I8. If the first pressure created adjacent the diaphragms I1 and i8 is above atmospheric the micro-switch l'l will operate to close an obvious energizing circuit for the solenoid waves.

Mi. Under the influence of the magnetic field created by the solenoid, the armature it and plug I12 will be actuated (to move to the right in Fig. 1) so that the plug it closes the throat of the horn H and thereby seals the diaphragm it from the atmosphere. Consequently, the diaphragm ill will be protected from the pressure waves created by the source.

If the first pressure created adjacent the diaphragms ill and i8 is below atmospheric, the micro-switch it will operate to close an obvious energizing circuit for the solenoid M and the plug 12 will be actuated to seal the diaphragm ill from the atmosphere.

When either energizing circuit for the solenoid Id is closed, the relay becomes energized so that the armature 2d engages the contact 23 and a circuit is completed'through coil it, source it, winding I6, contact 233, armature M and switch Consequently, the plug member is locked in position and the diaphragm it is protected against subsequent blasts from the source 26. When normal atmospheric conditions again prevail, the locking circuit may be broken by opening the switch 25 as a result of which the solenoid it becomes deenergized and the plug 12 is retracted, as by a spring 21 coupled at one end to the armature i3 and fixed at its other end.

In installations where atmospheric conditions likely to affect the diaphragm ill prevail frequently or for a large part of the time, the spring 2'! maybe so associated with the armature it that normally the plug 2 closes the throat of the horn M. The solenoid may then be energized, when it is desired to operate the loudspeaker, to move the armature id in such direction (to the left in Fig. 1) that the plug member is moved away from the throat of the horn Ill and the diaphragm iii may radiate into the atmosphere. The solenoid Ml may be thus energized, for example, through a cir'cuit including a switch 28 in series with the coil and the source 15 as indicated in dotted outline in Fig, 1. Alternatively, if the diaphragm actuating unit of the loud-speaker is connected in circuit with atransmitter, such as a microphone, the diaphragms 2t and 21 may be disposed in proximity to the microphone and operated by speech waves to close an energizing circuit for the solenoid as described heretofore. This circuit could be opened to restore the plug to its closed position by opening the switch 25.

Although in Fig. 1 a single loud-speaker has been shown, it is obvious that a plurality of loudspeakers may be controlled simultaneously. For example, each of a plurality of loud-speakers may be provided with a closure arrangement including an armature, plug member andcoil and in the energizing circuits.

been shown, a plurality of sets may be provided each adjacent a source of deleterious pressure In such case, the several sets of switches may be connected in parallel so that operation of any switch causes energization of all the coils M.

In the illustrative embodiment shown in Figs. 2 and 3, the loud-speaker may be of the general construction disclosed in Patent 1,707,545 granted April 2, 1929 to Edward C. Wente and com prises a magnet. having pole-pieces 29 and 3d spaced to form an annular air-gap ill, the magnet being energized by a fleld coil 32. Mounted 'upon the magnet is a diaphragm it having an inwardly dished portion 33 and having secu ed thereto an actuating coil 34 which is disposed in the air-gap 31. A coupler member 35 overlies the diaphragm and has an outlet 36, preferably coaxial with the diaphragm, internally threaded to accommodate the throat of a suitable horn. Disposed in the chamber between the diaphragm and the coupler member is a movable plug 3'! the inner surface of which may be substantially of adapted to slide in a corresponding aperture ti in the coupler member. Suitable helical springs d2 have their ends abutting the coupler member 35 and the armature l3 and serve to hold the plug 3'? normally against the inner surface of the coupler member so that the outlet 36 is closed.

A magnetic system for actuating the armature i3 is mounted upon the loud-speaker, as by nonmagnetic brackets dd secured to the pole-piece 30 by machine screws M, and comprises a core t5 and parallel arms it extending between the armature i3 and the coupler member The core 45 is encompassed by a suitable solenoid M, which may be energized in the manners described heretofore in connection with Fig. 1.

As will be apparent, when the solenoid id in the arrangement disclosed in Figs. 2 and 3 is energized, the magnet it, Mi is magnetized and consequently the armature i3 is attracted to and contacts with the arms #6 thereby moving the plug 3i out of engagement with the inner surface of the coupler member and opening the passageway 36. The arms M and armature l3 preferably are so spaced and the juxtaposed surfaces of the plug anddiaphragm so shaped that when the armature contacts with arms it the passageway between'the dished portion 33 and the inner surface of the plug till increases exponentially as described in the Wente patent aforementioned.

Upon deenergization of the coil M; the magnet structure d5, M is demagnetized and the springs d2 move the armature it! outwardly so that the plug it again closes the passageway M.

In the embodiment illustrated in Fig. 4, the various parts are so arranged that normally, that is with the coil iii not energized, the diaphragm it is in communication with the atmosphere through the passageway 36 and the horn associated therewith. As shown in this figure, the

arms Mi overlie the armature l3 and the springs I W normally hold the armature in such position that the plug it forms the desired passageway, for example of exponentially flaring form, between the dished portion 33 of the diaphragm and the inner surface of the plug. The requisite clearance may be established, for example, by collars or stops M on the pins 38, adapted to abut shoulders 48 on the coupler member-35.

When the coil ll is energized, as for example in the manners described heretofore with reference to Fig. 1, the armature i3 is drawn toward egress of the pressure waves impinging upon the 75 plug member. As will be apparent these vents are sealed by the pins 40- when the loud-speaker is operating.

Although specific embodiments of the invention have. been shown and described it will be understood, of course, that various modifications may be made therein without departing from the scope and spirit of this invention as defined in the appended claims. For example, although two auxiliary diaphragms and associated switches have been shown in Fig. 1, a single diaphragm and two switches may be employed, one switch being adapted to close when the diaphragm moves in one axial direction and the other to close when the diaphragm moves in the opposite direction. Alternatively a single dlaphragm and a single two-way switch may be utilized. 7

What is claimed is:

1. Sound translating apparatus comprising a diaphragm, means defining a sound passageway in communication'with said diaphragm, a. movable plug member in said passageway, electromagnetic means for moving said plug member to open or close said passageway, and a control circuit for said electromagnetm means.

2. In combination, a diaphragm, means defining a sound passageway in communication therewith, a movable plug member adapted to close said passageway, electromagnetic means for actuating said plug member, an energizing circuit for said electromagnetic means including a circuit controlling member, and means responsive to unnormal atmospheric pressures in the vicinity of said diaphragm for actuating said circuit controlling member.

3. In combination, an acoustic device including a diaphragm and means defining a passageway coupling said diaphragm to the atmosphere, and means for protecting said diaphragm against deleterious atmospheric pressures comprising a member adapted to close said passageway and means responsive to atmospheric pressure waves for actuating said member to close said eway.

4. In combination, an acoustic device including a diaphragm and means defining a sound passageway coupling said diaphragm to the atmosphere, and means for protecting said diaphragm against deleterious atmospheric pressures comprising a closure member movably mounted in said passageway, electromagnetic means for actuating said closure member, an-energizing circuit for said electromagnetic means including a ciring means, an energizing circuit for said elec-' tromagnetic means, means responsive to subnormal atmospheric pressures for closing said circuit,

1 net.

magnetic means including a pair of circuit controlling members connected in parallel, and actuating means for closing said members including a pair of pressure responsive members one of which is adapted to actuate one of said circuit controlling members in response to subnormal atmospheric pressures and the other .of which is adapted to actuate the other of said circuit controlling members in response to abnormal atmospheric pressures.

9. Sound translating apparatus comprising a diaphragm, means defining a sound chamber adjacent said diaphragm and having an opening to the atmosphere therein, a movable plug member in said chamber adapted to close said opening, a magnetic armature coupled to said plug mem-v ber and movable therewith, and means for actuating said armature including a magnet having poles adjacent said armature and a magnetizing co-il for said magnet.

10. Sound translating apparatus in accordance with the next preceding claim comprising resilient means opposing movement of said armature by said actuating means.

11. Sound translating apparatus comprising a diaphragm, means defining a sound passageway in communication with said diaphragm, a movable plug member in said passageway and adapted to seal it acoustically, a magnetic armature connected to said plug -member and movable therewith, means for holding said plug member in such position that it seals said passageway, and means for magnetically moving said armature to hold said plug member in such position that said passageway is opened.

12. Sound translating apparatus comprising a diaphragm, means defining a sound passageway in communication with said diaphragm, a movable plug member adapted to.close said passageway, resilient means holding said member in such position that said passageway is open, a magnetic armature coupled to said member, and

electromagnetic means for actuating said armaand resiliently mounted on said coupler member,

a magnet having poles adjacent said armature, and an energizing coil associated with said mag- HARRIS F. HOPKINS. 

